LTC3726 Datasheet, PDF (16/16 Pages) Linear Technology – Secondary-Side Synchronous Forward Controller

LTC3726
TYPICAL APPLICATIO
V_IN+
L1 1µH
1µF
100V
1µF
100V
x3
Si7852DP
Si7852DP
MURS120
T1
••
9:2
Si7336ADP
MURS120
10Ω
0.25W
1nF
1nF
100V
100V ^10Ω
0.25W
1.2Ω
L2 1.2µH
CMPSH1-4
Si7336ADP
×2
1µF
5K
FZT690B
V_IN–
365k
1%
1nF
30mΩ
1W
2.2nF
250V
2mΩ
2W
7.5V
10µF
25V
100Ω
100k
680pF
FQT7N10
BAS21 ^0.22µF
NDRV
BOOST TG TS BG IS
L1: VISHAY IHLP-2525CZ-01
L2: COILCRAFT SER2010-122
T1: PULSE PA0807
T2: PULSE PA0297
UVLO
LTC3705
FB/IN⁺
100Ω
T2
0.1µF ^{• •}
100Ω 100Ω
1nF
1µF
FG
I_S–
I_S+
PT⁺
SW SG
CZT3019
V_CC
LTC3726
FS/SYNC
FB/PHASE
ITH
2.2µF
16V
2.2µF
25V
V_CC
SS/FLT
FS/IN^–
GND PGND VSLMT
470pF
5k
2:1
PT^–
RUN/SS GND PGND SLP MODE
680pF
15k
1%
33nF
162k
33nF
100k
20k
Figure 5. 36V-72V to 3.3V/20A Isolated Forward Converter
(See Typical Performance Characteristics)
V_OUT+
330µF
6.3V
×3
V_OUT–
102k
1%
22.6k
1%
3726 F05
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PART NUMBER
LT1534
DESCRIPTION
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LT1619
LT1681/LT3781
LT1725
Low Voltage Current Mode Controller
Dual Transistor Synchronous Forward Controller
General Purpose Isolated Flyback Controller
LTC1871
LT1910
LT1952
LTC3440
LTC3704
Wide Input Range, No R_SENSE™ Controller
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Positive-to-Negative DC/DC Controller
LTC3705
Two-Switch Forward Converter Gate Driver and Controller
LT3706
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LTC3725
Two-Switch Forward Controller
No R_SENSE is a trademark of Linear Technology Corporation.
COMMENTS
Reduces Conducted and Radiated EMI, Low Switching Harmonics,
20kHz to 250kHz Switching Frequency
1.9V ≤ V_IN ≤ 18V, 300kHz Operation, Boost, Flyback, SEPIC
Operation Up to 72V Maximum
No Optoisolator Required, Accurate Regulation Without User Trims,
50kHz to 250kHz Switching Frequency, SSOP-16 Package
Operation as Low as 2.5V Input, Boost, Flyback, SEPIC
8V to 48V Supply Range, Protected –15V to 60V Supply Transient
25W to 500W; Synchronous Controller
Synchronous, Single Inductor, No Schottky Diode Required
2.5V ≤ V_IN ≤ 36V, No R_SENSE Current Mode Operation,
Excellent Transient Response
Use with LTC3726, Isolated Power Supplies, High Speed Gate Drivers
Scalable Output Power; Self-Starting Architecture
Synchronous; ZVS Operation; 24-Pin SSOP
On-Chip Gate-Driver; Fast Startup
16 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ^● FAX: [phone] ^● www.linear.com
3726fb
LT 0207 REV B • PRINTED IN THE USA
© LINEAR TECHNOLOGY CORPORATION 2006